Legionella control in the University of Sheffield Legionella Awareness for Departmental representatives - PowerPoint PPT Presentation

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Legionella control in the University of Sheffield Legionella Awareness for Departmental representatives. What is Legionella?. A naturally occurring bacterium Found in most water systems Often present in mains water Easily colonises most domestic water systems – hot and cold.

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Legionella control in the University of Sheffield Legionella Awareness for Departmental representatives

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Legionella control in the University of SheffieldLegionella Awareness for Departmental representatives

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What is Legionella?

  • A naturally occurring bacterium

  • Found in most water systems

  • Often present in mains water

  • Easily colonises most domestic water systems – hot and cold

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Requirements for Growth?

  • Optimum temperature range of 20 - 45 ⁰C

  • Food source (other bacteria & sediments)

  • Prefers stagnant conditions

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Route of Infection?

  • Primarily through inhalation of aerosols, fine droplets & mists

  • Can be contracted by choking on contaminated water

  • Statistically most susceptible

    - 50 to 70 year olds

    - Males

    - Smokers

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How big a risk?

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Legionnaire’s Disease

  • Potentially fatal form of pneumonia –

    5-30% fatality rate

  • 200-300 cases of infection in England & Wales annually

  • Incubation period 2-10 days - typically 3-6days

  • Legionella pneumophila – 23 sub types

  • HSE view Legionnaire's Disease as “preventable” assuming management failure!

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Legionnaire's Disease

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  • The Health and Safety at Work etc Act 1974

  • Management of Health & Safety at Work Regulations 1999

  • COSHH 2002

  • ACOP L8 (see front cover)

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L8 Guide to Successful Control


  • Management regime in place

  • Risk Assessments

  • Control regime

  • Maintenance and upgrade

  • Review

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Risk Assessments should:

  • Identify & quantify relevant wet systems plus equipment holding / circulating water

  • Assess potential for Legionella growth

  • Identify who is at risk

  • Assess the potential for bacterial transfer

  • Quantify and prioritise the risks

  • Determine suitable means of control

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UoS Responsibilities 1

  • Statutory Duty Holder who is ultimately responsible – Registrar & Secretary

  • Appointed Responsible Person for day to day management – Director of Estates

  • Deputy Responsible Person to cover holidays and illness – Head of Engineering Operations

  • Responsibility cannot be delegated

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UoS Responsibilities 2

  • Policy for the Control of Legionella bacteria

  • Management structure in place with Contractors charged with carrying out: -

    • Legionella Risk assessments of all buildings

    • Treatment of water assets where required

    • Sampling and analysis of water systems

    • Remedial works incl. removing “dead-legs”

  • 5 Zones - Engineers managing Contractors

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Current Position

  • Current regime in place for > 2 years

  • 95% buildings assessed (some low risk o/s)

  • Current costs ~ £250,000 pa

  • Monitoring of sample results on-line

  • Legionella Procedures Manual in place

  • Legionella Control Steering Group – 3 meetings per year chaired by Prof R F Jackson

  • Policy and Procedures on Safety Services


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Typical Systems at Risk

  • Cooling Towers

  • Domestic hot & cold water systems

  • Water features incl. ornamental fountains

  • Equipment producing aerosols, mists or droplets from stored water sources including showers & humidifiers

  • Equipment holding / circulating

    water at 20 - 45⁰ C

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Examples of lab & workshop equipment

  • Water tanks & baths

  • Spray taps

  • Water recirculation systems for cooling

  • Rarely used taps & showers (even at home)

  • Misting equipment

  • Dentistry tools

  • Oil / water emulsions for

    lubricating lathes

  • Mobile AC equipment with water

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Controlling Legionella bacteria

  • Temperature monitoring

  • Controlled release of water spray

  • Avoid temp. conditions 20 - 45⁰ C

  • Avoid water stagnation - empty & clean regularly

  • Avoid materials which harbour bacteria

  • Maintain cleanliness of spray outlets

  • Water treatment where necessary

  • Ensure correct & safe operation of system

  • Flushing regime for rarely-used outlets

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What Departments need to do - 1

  • Identify a Nominated Person to help you manage Legionella risks in your Department

  • Identify & record all : -

    • water-containing equipment which operates in the temperature range 20-45⁰C

    • all rarely-used taps & showers

    • all equipment supplied from stored water sources producing sprays, mists or aerosols

  • Assess the risk of Legionella growth in each

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What Departments need to do - 2

  • Check Legionella Procedures Manual for information of the management of specific items of laboratory equipment

  • If your equipment is not listed, determine the best means of reducing Legionella risks – if needed, contact Department of Estates for help

  • Consider which treatment options are the most appropriate from the next slide

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Treatment / remedial options

  • Monitor temperatures; 20-45⁰C = risk range

  • Every 2 weeks - heat water to 60⁰C for 5 mins

  • Add disinfectants / Chloros as advised

  • Empty out the water system, thoroughly clean & refill with fresh water every month

  • Clean & disinfect spray heads every month

  • Flush rarely-used outlets weekly

  • Arrange with Estates for removal of “dead-legs”

  • Arrange with Estates for samples to be taken if risk exists (sampling is NOT a control measure – it takes 10 days for results to be sent through – it monitors whether your controls work)

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Next step

  • Record all actions taken and results received.

  • Review the efficacy of the treatment regime by checking the results of analyses received

  • Re-assess the risk assessment if there are any changes to the operating parameters or the system layout

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Drinking water coolers

  • 2 types generally available:

    • Using large bottles of mineral water

    • Plumbed-in units

  • Legionella is not reported to be a problem with water bottle coolers, usually work outside “critical temperature range”,

  • 1 reported instance of Legionella bacteria being isolated from Activated Carbon filters in a plumbed-in unit in New Zealand – replace as recommended by manufacturer.

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